Deep Dream Images¶
Convoutional Neural Networks (CNN) are state of the art algorithms for computer vision and image processing. One fun thing you can do is to produce Deep Dream images. Here is some backgound from Stanford's cs231n class:
In the summer of 2015, Google released a blog post describing a new method of generating images from neural networks, and they later released code to generate these images.
The idea is very simple. We pick some layer from the network, pass the starting image through the network to extract features at the chosen layer, set the gradient at that layer equal to the activations themselves, and then backpropagate to the image. This has the effect of modifying the image to amplify the activations at the chosen layer of the network.
For DeepDream we usually extract features from one of the convolutional layers, allowing us to generate images of any resolution.
We can implement this idea using our pretrained network. The results probably won't look as good as Google's since their network is much bigger, but we should still be able to generate some interesting images.
I generated a few Deep Dream images using a combination of python code I wrote and code supplied by cs231. This notebook shows the python code and images. The images are wild, here is an example of applying the deep dream process to an image. The starting image and the deep dream image:
import time, os, json
import numpy as np
from scipy.misc import imread, imresize
import matplotlib.pyplot as plt
from cs231n.classifiers.pretrained_cnn import PretrainedCNN
from cs231n.data_utils import load_tiny_imagenet
from cs231n.image_utils import blur_image, deprocess_image, preprocess_image
%matplotlib inline
plt.rcParams['figure.figsize'] = (10.0, 8.0) # set default size of plots
plt.rcParams['image.interpolation'] = 'nearest'
plt.rcParams['image.cmap'] = 'gray'
# for auto-reloading external modules
# see http://stackoverflow.com/questions/1907993/autoreload-of-modules-in-ipython
%load_ext autoreload
%autoreload 2
data = load_tiny_imagenet('cs231n/datasets/tiny-imagenet-100-A', subtract_mean=True)
model = PretrainedCNN(h5_file='cs231n/datasets/pretrained_model.h5')
def deepdream(X, layer, model, **kwargs):
"""
Generate a DeepDream image.
Inputs:
- X: Starting image, of shape (1, 3, H, W)
- layer: Index of layer at which to dream
- model: A PretrainedCNN object
Keyword arguments:
- learning_rate: How much to update the image at each iteration
- max_jitter: Maximum number of pixels for jitter regularization
- num_iterations: How many iterations to run for
- show_every: How often to show the generated image
"""
X = X.copy()
learning_rate = kwargs.pop('learning_rate', 5.0)
max_jitter = kwargs.pop('max_jitter', 16)
num_iterations = kwargs.pop('num_iterations', 100)
show_every = kwargs.pop('show_every', 25)
for t in xrange(num_iterations):
# As a regularizer, add random jitter to the image
ox, oy = np.random.randint(-max_jitter, max_jitter+1, 2)
X = np.roll(np.roll(X, ox, -1), oy, -2)
dX = None
############################################################################
# TODO: Compute the image gradient dX using the DeepDream method. You'll #
# need to use the forward and backward methods of the model object to #
# extract activations and set gradients for the chosen layer. After #
# computing the image gradient dX, you should use the learning rate to #
# update the image X. #
############################################################################
scores, cache = model.forward(X, end=layer)
dx, grads = model.backward(scores, cache)
X += learning_rate * dx
############################################################################
# END OF YOUR CODE #
############################################################################
# Undo the jitter
X = np.roll(np.roll(X, -ox, -1), -oy, -2)
# As a regularizer, clip the image
mean_pixel = data['mean_image'].mean(axis=(1, 2), keepdims=True)
X = np.clip(X, -mean_pixel, 255.0 - mean_pixel)
# Periodically show the image
if t == 0 or (t + 1) % show_every == 0:
img = deprocess_image(X, data['mean_image'], mean='pixel')
plt.imshow(img)
plt.title('t = %d' % (t + 1))
plt.gcf().set_size_inches(8, 8)
plt.axis('off')
plt.show()
return X
From start to finish¶
This cell shows the progression of a starting image into a well developed deep dream image. In this case the starting image is from an awards ceremony for the Mille Lacs Kite Crossing snow kite race. The staring image turns into something soft and squishy.
def read_image(filename, max_size):
"""
Read an image from disk and resize it so its larger side is max_size
"""
img = imread(filename)
H, W, _ = img.shape
if H >= W:
img = imresize(img, (max_size, int(W * float(max_size) / H)))
elif H < W:
img = imresize(img, (int(H * float(max_size) / W), max_size))
return img
filename = '2016-03-04 20.30.27.jpg'
max_size = 256
img = read_image(filename, max_size)
plt.imshow(img)
plt.axis('off')
# Preprocess the image by converting to float, transposing,
# and performing mean subtraction.
img_pre = preprocess_image(img, data['mean_image'], mean='pixel')
out = deepdream(img_pre, 7, model,
learning_rate=1e4,
num_iterations=100)
From soothing to disturbing¶
The follow deep dream progression starts with a soothing winter image taken at dusk near Jakson Hole, WY. I find the Deep Dream images disturbing as they remind me of visual glitches associated with the onset of a migrane headache.
filename = '20160202_172938.jpg'
max_size = 256
img = read_image(filename, max_size)
plt.imshow(img)
plt.axis('off')
# Preprocess the image by converting to float, transposing,
# and performing mean subtraction.
img_pre = preprocess_image(img, data['mean_image'], mean='pixel')
out = deepdream(img_pre, 7, model,
learning_rate=1e4,
num_iterations=300)
filename = 'ducks.jpeg'
max_size = 256
img = read_image(filename, max_size)
plt.imshow(img)
plt.axis('off')
# Preprocess the image by converting to float, transposing,
# and performing mean subtraction.
img_pre = preprocess_image(img, data['mean_image'], mean='pixel')
out = deepdream(img_pre, 7, model,
learning_rate=1e4,
num_iterations=300)
Here is a question, is the following statement true for you?
Deep Dream images are interesting since I feel they reflect or echo, sometimes, how I might dream.
It is for me.